This invention relates generally to a method and system for synchronizing multiple data signals and more particularly to a method and system for synchronizing an EKG waveform generated via an electrocardiogram (EKG) with an x-ray image generated via a computed tomography (CT) imaging system.
In many cardiac applications, it is desirable to have the ability to display a CT image of a patients' heart along with a simultaneously generated patient EKG waveform. This would allow a physician or technician to visually observe the physical condition of the patients' heart while simultaneously observing the cardiac electrical function of a patient. However, if the heart is moving or beating (cardiac motion) during the scanning process, the CT projection data may include motion artifacts and other noises making accurate reconstruction of the CT image more difficult, or in some cases impossible.
One technique currently available to reduce the effect of cardiac motion is to synchronize the CT imaging system with the patient heart cycle so that the CT scans only occur between heart beats. In order to accomplish this task, current cardiac scanning techniques synchronize a patient CT scan with the electrical heart cycle of the patient via an EKG monitoring device communicated with a CT imaging system. Referring to FIG. 1, an example of a patient EKG waveform 100 is shown and includes an R-Peak 102 and an exposure indicator 104, wherein exposure indicator 104 identifies the period in EKG waveform 100 where the CT scan and thus patient exposure occurs. As can be seen, exposure indicator 104 is disposed between heartbeats indicating that the CT scan occurred while the patients' heart was resting.
One problem with this technique is that, although most EKG monitoring devices provide a means to read EKG waveform data as it is being collected, most CT imaging systems do not. As a result, a delay in time occurs between the collection of the EKG data and the collection of the CT projection data making accurate correlation between the EKG data and the CT projection data extremely difficult or impossible. Therefore, there is a need for a method that facilitates the correlation of EKG data and CT projection data, wherein the method utilizes existing CT imaging systems and EKG monitoring devices and wherein the method does not significantly increase the data collection time.